X & XA Class

The TGR X class was the first mainline diesel-electric locomotive purchased by an Australian government railway system. These 32 locomotives replaced steam locomotives on most mainline trains, although steam locomotives still saw occasional use on various secondary and special services up to 1975. Tenders were called in 1946 for five or ten diesel locos, and this was let later in the year to the English Electric Company in the UK for ten locos. A second batch of ten were ordered following the 1948 review, and finally a third batch of twelve were ordered in 1949. All locos were ordered well before construction had commenced of the first units. The locos were delivered in a continuous stream between September 1950 and December 1952, with the first twenty being constructed at the Vulcan Foundry works and the final twelve being built at EE's own Dick Kerr works. The locos initially operated singularly (where they were slightly less powerful, although faster than the 1920s built steam locos they were to replace), or coupled in pairs with a single crew which where their true benefits lay. By the 1970s, it was not uncommon for three X, XA or Y locomotives to operate together, although when an X class locomotive was involved the others were down rated to this lower haulage capacity.

Five X class were rewired between 1961 and 1970 to give better operation at low speed with the more powerful Y class locomotives then being constructed. The unmodified X locos were susceptible to overheating when hauling heavy trains on long grades, and the modifications made them more suitable to operation on the southern part of the Main Line. Other modifications to both X and XA class locomotives included the fitting of automatic couplers and sliding windows.

Delivered in a plain dark green (later relived with a cream strip and or chevron), all were progressively painted red and cream from about 1954. From 1971 the standard colour scheme was yellow with black stripes and four locos were repainted AN green from 1981Despite the influx of locomotives from South Australia and then Queensland, the last of the locos was not removed from service until 1988 when the final vacuum braked general freight services ended.